Im not sure how it work on steam. My guess would be you could go through steam and request a new password for aces high after you log into your steam account. Getting logged in through the aces high site is a totally different setup. They are not interchangeable.
Options,
Login into steam and request help through that portal.
Call HTC at (817) 431 - 8840 and ask Hitech to fix it.
Cancel your account on steam and create a new one at the Aces High website or steam. You will lose all of your points/score and will have to use a different name, but you'll be in.